WRRC Weekly Wave: Lees Ferry Streamgage Turns 100

On October 1, 2021, the Colorado River streamflow gauging station at Lees Ferry celebrated its 100th anniversary. As the source of key data used in implementing the foundational agreements and laws governing Colorado River allocations, the gage merits special attention. Located at the mouth of the Grand Canyon, close to the point that the Colorado River Compact defines as the divide between the Upper and Lower Basins, it is used to measure the river flow from the Upper to the Lower Basin. According to the 1922 Compact, this flow must be at least 75 million acre-feet in any consecutive 10-year period. Installed by USGS to study the hydrology of the watershed a year before the Compact was negotiated, it has remained “one of the most … accurate large-river gages in the U.S.” Jim Leenhouts, Director of the USGS Arizona Water Science Center, credits its “consistent, long-term scientific information” with helping decisionmakers cope with changing conditions through time. In honor of the gage’s anniversary, the USGS has compiled links, photos, reports, and studies (listed here) relating to the Lees Ferry gage and its vital role in the history of Colorado River management.